body {
  background-image: url('../images/pngtree-abstract-line-background-with-dynamic-shapes-image_372832.jpg');
  background-repeat: repeat-x;
  background-size: 100% 100%;
  font-size: medium;
}

/*模态框*/
.modal {
  display: none;
  /* 默认隐藏 */
  position: fixed;
  /* 根据浏览器定位 */
  z-index: 1;
  /* 放在顶部 */
  left: 0;
  top: 0;
  width: 80%;
  /* 全宽 */
  height: 80%;
  /* 全高 */
  overflow: auto;
  /* 允许滚动 */
  background-color: rgba(0, 0, 0, 0.4);
  /* 背景色 */
}

/*模态框内容*/
.modal-content {
  display: flex;
  /*采用flexbox布局*/
  flex-direction: column;
  /*垂直排列*/
  position: relative;
  background-color: #fefefe;
  margin: 15% auto;
  /*距顶部15% 水平居中*/
  padding: 20px;
  border: 1px solid #888;
  width: 80%;
  animation: topDown 0.4s;
  /*自定义动画，从模态框内容上到下出现*/
}

@keyframes topDown {
  from {
    top: -300px;
    opacity: 0
  }

  to {
    top: 0;
    opacity: 1
  }
}

/*模态框头部*/
.modal-header {
  display: flex;
  /*采用flexbox布局*/
  flex-direction: row;
  /*水平布局*/
  align-items: center;
  /*内容垂直居中*/
  justify-content: space-between;
}

/*关闭X 样式*/
.close {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
}

.close:hover {
  color: black;
  text-decoration: none;
  cursor: pointer;
}